TerraTrike Lumbar Support CushionFor riders looking for added lower back support, the customizable Lumbar Support Set can be tuned to anyones comfort needs. Using three removable foam inserts of varying thickness and shape, the set can be molded to provide support precisely where the rider needs it. To install, select the foam insert pieces desired, wrap in the included breathable mesh cover, and place the support between the mesh and adjustment straps of the seat.